Gear Grind continues ... tried everything. What to do next?

[Volksparts]

Yeah that clutch pedal adjustment and then the weighted shift knob over 500 g has made the biggest difference in the world for me. I saw that you're running a different shifter assembly so that's pretty much what I'm doing also. Feel like I said those two were what got rid of the occasional grinding.

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[oak]

This is my theory of what is happening with those that are experiencing 2nd grinds and lock outs... during the assembly and mfg of the gear boxes there were some that were not completely filled to capacity, as what I experienced in my own r. I measured what was drained it was shy of .6 qt no leaks clean and dry. I refilled to approx 2.5 qt fact requests 2.3 qt so approx 1.7 qt was drained when I checked. this short fill has a direct impact on the synchros due to lack or fluid and insufficient fluid pressures.

I think there's a direct correlation to early synchro wear which causes a permanent issue if not addressed early on. I think that's why for many fluid swap had helped but not resolved the problem as the synchros have worn beyond and have permanent damage. from my personal experience once I noticed the grinds and lock out I had my dealership check it out and they couldn't reproduce the problem, I just flushed and refilled w GM AC delco and have not experienced any grinds or lock out, it was an immediate and noticeable difference. it's a thing of the past for me.

 

[Lust]

This is my theory of what is happening with those that are experiencing 2nd grinds and lock outs... during the assembly and mfg of the gear boxes there were some that were not completely filled to capacity, as what I experienced in my own r. I measured what was drained it was shy of .6 qt no leaks clean and dry. I refilled to approx 2.5 qt fact requests 2.3 qt so approx 1.7 qt was drained when I checked. this short fill has a direct impact on the synchros due to lack or fluid and insufficient fluid pressures.

I think there's a direct correlation to early synchro wear which causes a permanent issue if not addressed early on. I think that's why for many fluid swap had helped but not resolved the problem as the synchros have worn beyond and have permanent damage. from my personal experience once I noticed the grinds and lock out I had my dealership check it out and they couldn't reproduce the problem, I just flushed and refilled w GM AC delco and have not experienced any grinds or lock out, it was an immediate and noticeable difference. it's a thing of the past for me.

If this were true, you would experience this in all gears.

 

[oak]

If this were true, you would experience this in all gears.

not necessarily, depending on most exposed gear as the weakest link in the chain would wear first. I think that's why it starts as 2nd gear grinds and works out to lock outs in the higher gears.

 

[Lust]

not necessarily, depending on most exposed gear as the weakest link in the chain would wear first. I think that's why it starts as 2nd gear grinds and works out to lock outs in the higher gears.

And why do you think that the 2nd gear synchro is “the weakest link”?

 

[oak]

1-2 shifts take the most load and this puts more initial wear and this initiated grinds as the synchros wear once they are worn it doesn't matter what you do it's done all the pedal adjustments, trans fluid may help but it won't be like new.

 

[Lust]

1-2 shifts take the most load and this puts more initial wear and this initiated grinds as the synchros wear once they are worn it doesn't matter what you do it's done all the pedal adjustments, trans fluid may help but it won't be like new.

Well you would be correct that the 2nd gear synchro has a lot of work to do because of the gear ratio difference between 1-2. I explained all of that in my Gear Grind thread. It doesn’t really confirm your theory of under filled transmissions though.

 

[oak]

Well you would be correct that the 2nd gear synchro has a lot of work to do because of the gear ratio difference between 1-2. I explained all of that in my Gear Grind thread. It doesn’t really confirm your theory of under filled transmissions though.

Well one thing for sure is something is a mis and there is a cause due to increase in grind and lock out over time. This is most likely a premature wear issue. I used to build drag transmission in type 1 VW air cooled and some pcar experience this was common when second gear synchros start to wear.

 

[blayed]

https://www.civicx.com/forum/threads/transmission-grinds-lockouts-causes-solutions.62471/

I think this is the key passage:

" Poor technique also comes into play as I see most inexperienced drivers start to move the gear lever before their foot is fully on the ground. The grind becomes more frequent if the clutch pedal is poorly adjusted. The synchro simply can't keep up at this point and it causes a grind. The best technique is to fully depress the clutch before applying any pressure to the gear selector. "

 

[Heavy Foot]

And why do you think that the 2nd gear synchro is “the weakest link”?

80's Ferrari's had bad second gear synchro's as well.

 

[blayed]

Just wanted to give everyone an update. I adjusted the clutch pedal and focused on not applying any pressure onto the shifter until the clutch pedal was fully in place. In one week I had one gear grind but admittedly I wasn't paying attention and didn't clutch in all the way. This is a big improvement from daily! I had a friend drive it for 30mins and he could not replicate which makes me thing it is mostly technique based. I did however order some GM Synchromesh and the hasport RMM in the hope that at least it makes the shifting experience better

 

[blayed]

I wanted to give a final update with some interesting findings.

I replaced the transmission fluid to GM synchromesh and added the hasport RMM. Wow! What a world of difference. I went from daily grinding to not having one the month since. During the process I took a sample of my amsoil MTF and sent it to blackstone.

What I found is that my viscosity was LESS than the normal range for the OEM fluid! Even though Amsoil claims it is much higher, either I got a bad batch or in 10k miles it became less viscous. Blackstone doesnt see any oxidation or wear so most likely it is a bad batch. See attachment. For reference:

For kinematic viscosity at 100C:
OEM range (from blackstone): 9.9-15.3
Amsoil (Claimed): 10.1
Amsoil (actual, after 10k miles): 8.19
GM Synchromesh FM: 10.05

Because of this, I can no longer recommend amsoil MTF and it is one of the reasons which I believe contributed to my gear grinds. The GM synchromesh, hasport RMM, KZCMC, and clutch pedal adjustment, and technique modification seemed to have the biggest help and improvement.

 

[tacthecat]

Interesting

 

[hesitation]

amsoil sucks compared to GM synchromesh. glad to see someone got a test back to prove it more definitively.

 

[Centripetal]

OEM range (from blackstone): 9.9-15.3

Thanks for sharing this great data.

I think they might have improvised on the viscosity. IIRC, Honda MTF is 75W-80 , which has a viscosity range 8.5 to 11 .

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